Eoraptor, binomial name Eoraptor Lunensis, meaning 'dawn thief', was a species of dinosaur classified under the saurischia order of dinosauria. It is widely considered to be one of the worlds earliest dinosaurs. The Eoraptor lived during the late Triassic Period, around 230 to 190 million years ago (mya), and is believed to resemble the ancestor of all dinosaurs. It is known by well-preserved fossil records found in Argentina.

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The Eoraptor, was given the name raptor but it has no relations to the Velociraptor or any dromaeosauridea. Like many early dinosaurs, had a relatively small body in comparison to dinosaurs of later periods. It had a thin body that was approximately one metre in length when fully developed, and weighed approximately 10 kilograms. A bipedal carnivore, the Eoraptor ran upright on its hind legs, while its fore limbs were only half the length of the hind legs. Each fore limb ended in a five digit hand, with three of the digits ending in large claws that were believed to be used to catch and handle prey. While it was believed to have eaten small animals, due to its like swift speed and sharp claws, the Eoraptor also possessed both herbivorous and carnivorous teeth, leading to suggestions that it may have been omnivourous.

The fossil remains of the Eoraptor were first discovered in 1991 by paleontologist Paul Sereno, in the Ischigualasto Basin located in Argentina. Although the area is now barren as a desert badlands, it was believed to have been a river valley during the late Triassic. The Eoraptor was found in the Ischigualasto Formation, which was also the same foundation in which the early theropod Herrerasaurus was located. As the Eoraptor lacked the specialized hunting features of the major groups of later carnivorous dinosaurs, such as a sliding joint within the articulation of the lower jaw, which would have been used to hold larger prey, it was determined to be one of the world's earliest dinosaurs in 1993. Further evidence supporting the claim of its age was the fact that only some of the Eoraptor's teeth were curved and serrated, unlike later predators.thomas

As the Eoraptor possessed both herbivorous and carnivorous teeth, as well as five fully developed fingers, it was suggested that the Eoraptor was a more ancient species than even the Herrerasaurus. It is believed that only some prosauropods recently discovered in Madagascar of older age. The Staurikosaurus is considered to be possibly older, but due to its large size, it is expected to be of a later evolutionary period. However, as Staurikosaurus seems to have qualities present in both prosauropods and theropods, similar to Eoraptor's shared herbivorous and carnivorous tendencies, it has led researchers to question Eoraptor's primitive label, as its suggested omnivorous qualities were a key factor in its age deduction.